1. Field of the Invention
This invention relates to a novel resin composite consisting of a thermosetting resin and a thermoplastic resin or a photosensitive resin and a thermoplastic resin, and more particularly to a resin composite consisting of an epoxy resin and polyethersulphone (hereinafter abbreviated as PES) or a so-called PES modified epoxy resin, or a resin composite of an acrylic resin and polyether sulphone or a so-called PES modified acrylic resin as well as a method of producing the same.
2. Description of the Related Art
As the technique for the resin composite, there is a typical technique of improving the properties of a thermosetting resin by mixing the thermosetting resin with a thermoplastic resin. For example, in the mixed system (PES modified epoxy resin) of epoxy resin and polyethersulphone (PES), the toughness of the epoxy resin is improved by a co-continuous two-phase structure formed between the epoxy resin and PES (Keizo Yamarika and Takashi Inoue, Polymer, Vol. 30, p662 (1989)).
In the above PES modified epoxy resin formed by mixing two resins, the toughness is improved as compared with that of the epoxy resin alone because the PES modified epoxy resin has a resin structure as mentioned below. That is, in the mixed system of PES and epoxy resin such as bisphenol A-type epoxy resin, when it is cured at a high temperature, a state of completely dissolving the epoxy resin and PES (compatible state) is not formed but a state of separately mixing the thermosetting resin and the thermoplastic resin through spinodal decomposition (phase separating state) is formed. The latter case is apparently a state of connecting spherical epoxy domains to each other and regularly dispersing them into the matrix of PES, which is a so-called co-continuous two-phase structure between the epoxy resin and PES.
The co-continuous two-phase structure is formed by the phase separating state between the epoxy resin and PES, and is a structure of merely dispersing the spherical epoxy domains produced by spinodal decomposition into the PES matrix. Therefore, the effect of dispersing PES into the epoxy resin is developed, but the properties of PES itself can not be enhanced. Because, when a glass transition temperature of the composite having the co-continuous two-phase structure is measured by the measurement of dynamic viscoelasticity, two values of glass transition temperature peak are observed and hence it is considered that the interaction of the epoxy resin and PES as a matrix is weak.
The above knowledge on the co-continuous two-phase structure is true in case of a mixed system of a photosensitive resin and a thermoplastic resin, e.g. a mixed system of acrylic resin and polyethersulphone (PES modified acrylic resin)
It is, therefore, an object of the invention to provide a novel resin composite having properties inherent to the thermosetting resin such as epoxy resin or a photosensitive resin such as acrylic resin, for example, heat resistance and photosensitivity and exhibiting properties higher than those inherent to a thermoplastic resin such as PES or the like as well as a method of producing the same.
The inventors have first made studies with respect to a mixed system of a thermosetting resin and a thermoplastic resin as a resin composite in order to achieve the above object.
In the mixed system of thermosetting resin and thermoplastic resin such as an epoxy resin/PES mixed system, the epoxy resin and FES exhibit a so-called LCST (Low Critical Solution Temperature) type phase diagram in which both are miscible with each other at a low temperature but separate into two phases at a high temperature as shown in FIG. 1. However, when the epoxy resin is highly polymerized through the curing reaction and the glass transition temperature (Tg) of the resin raised above the curing temperature, molecular motion is fixed at this temperature and the phase separation can not be caused. Because, the phase separation is required to take molecular motion and diffusion.
The invention has been accomplished as a result of the above studies noticing the above facts. That is, the above object can be attained by controlling phase separation rate and curing rate of thermosetting resin and thermoplastic resin and compositing these resins so as not to form clear co-continuous two-phase spherical domains due to the phase separation between both the resins.
That is, a first aspect of the invention lies in a resin composite consisting of a thermosetting resin and a thermoplastic resin, or of a thermosetting resin, a thermoplastic resin and a resin having a photosensitivity, characterized in that the thermosetting resin and thermoplastic resin form a quasi-homogeneous compatible structure. In this case, the particle size of the resin particles constituting the quasi-homogeneous compatible structure is not more than 0.1 xcexcm as measured by means of a transmission type electron microscope (hereinafter abbreviated as TEM) and the peak value of the glass transition temperature of the resin as measured by dynamic viscoelasticity is one.
Moreover, the conditions for the measurement of dynamic viscoelasticity according to the invention are a vibration frequency of 6.28 rad/sec and a temperature rising rate of 5xc2x0 C./min.
On the other hand, the inventors have made studies with respect to the system of a photosensitive resin and a thermoplastic resin as another resin composite in order to attain the above object. As a result, it has been found that the photosensitive resin and the thermoplastic resin are cured and composited by controlling the phase separation rate and the curing rate so as not to form a clear co-continuous spherical domain structure due to the phase separation between these resins likewise the mixed system of thermosetting resin and thermoplastic resin, and as a result the invention has been accomplished.
That is, a second aspect of the the invention lies in a resin composite consisting of a photosensitive resin and a thermoplastic resin, characterized in that the photosensitive resin and thermoplastic resin form a quasi-homogeneous compatible structure. In this case, the particle size of the resin particles constituting the quasi-homogeneous compatible structure is not more than 0.1 xcexcm as measured by means of TEM and the peak value of the glass transition temperature of the resin as measured by dynamic viscoelasticity is one.
The conditions for the measurement of dynamic viscoelasticity in the invention are a vibration frequency of 6.28 rad/sec and a temperature rising rate of 5xc2x0 C./min.
According to a third aspect of the invention, there is the provision of a method of producing a resin composite by curing a thermosetting resin or a photosensitive resin mixed with a thermoplastic resin, which comprises curing the thermosetting resin and the thermoplastic resin at a curing rate exceeding a quasi-homogeneous phase forming point determined by at least one factor selected from a curing temperature of the thermosetting temperature, kind of a curing agent and presence or absence of photosensitivity, or curing the photosensitive resin and the thermoplastic resin at a curing rate exceeding a quasi-homogeneous phase forming point determined by a photocuring factor of the photosensitive resin
According to a fourth aspect of the invention, there is the provision of a method of producing a resin composite by curing a thermosetting resin or a photosensitive resin mixed with a thermoplastic resin, which comprises curing these resins at a phase separation rate not exceeding a quasi-homogeneous forming point determined by at least one factor of crosslinking density and molecular weight of uncured thermosetting resin or uncured photosensitive resin.
According to a fifth aspect of the invention, there is the provision of a method of producing a resin composite by curing a thermosetting resin or a photosensitive resin mixed with a thermoplastic resin, which comprises curing these resins at a curing rate exceeding the quasi-homogeneous forming point and a phase separation rate not exceeding the quasi-homogeneous forming point.
In these methods, it is desirable that the compounding ratio of the thermosetting resin or photosensitive resin to the thermoplastic resin is 15-50 wt % as a content of thermoplastic resin.